The present invention relates to a controlling apparatus of a high-pressure fuel pump for an internal combustion engine, and in particular, it relates to a controlling method of a high-pressure fuel pump for reducing noises within the internal combustion engine.
Conventionally, a controlling apparatus for a fuel pump is already known, for example, in the following Patent Document 1, which comprises a high-pressure fuel pump, for sucking fuel into a pressurizing chamber by changing the volume thereof upon basis of a relative movement of a cylinder and a plunger due to rotation of a cam, thereby sending the fuel sucked towards a fuel injection valve of an internal combustion engine under pressure, and a spill valve for opening/closing a fuel passage, which is provided between a spill passage for flowing out the fuel from the pressurizing chamber, and the pressuring chamber, whereby controlling a period when the spill valve is opened, so as to regulate or adjust an amount of fuel, which is transferred from the high-pressure fuel pump into the fuel injection valve under pressure. In this apparatus, an amount of fuel, which is transferred under pressure per one (1) cycle or stroke thereof, is decreased or reduced by reducing the number of times of fuel injections of the fuel injection valve per one (1) cycle of the transfer of fuel under pressure, when the internal combustion engine operates under the condition of a low load. With this, it is possible to shift a starting period for closing the spill valve up to the top dead center of the cam, i.e., bringing the cam speed to be small when the spill valve is closed, and thereby reducing a sound, which is generated upon closure of the spill valve. And, it is possible to suppress the operating sound of the spill valve from coming up to be relatively large, during the time of an idling operation when operating sounds of the internal combustion engine itself come down to be small, such as, a combustion sound, etc., for example.
Patent Document 1: Japanese Patent Laying-Open No. 2001-41088 (2001).
Thus, with such the conventional art as was mentioned above, since no consideration is paid upon a correlation between the equipments, which constitute the engine, other than the high-pressure fuel pump, therefore no attention is paid on an aspect that the noises are duplicated or overlapped by the equipments themselves, which constitute the engine, i.e., the noises are increased through a synergistic effect thereof.
The noises generated from the engine include, not only the noises caused by the high-pressure fuel pump, but also the noises caused by the injector (i.e., the fuel injection valve) and/or a moving valve, or due to the combustion, etc., for example. Those noises, although being not so large by itself, but sometimes could be felt to be noisy, in particular, due to the synergistic effect, when they are generated overlapping or duplicating with each other in the timing thereof. For example, the injector and the high-pressure fuel pump sometimes generate the noises (i.e., the operation sounds) accompanying with the drives thereof, respectively, and if they are overlapped with each other, they are sometimes felt to be a noise, in particular, being large for the sense of hearing of a human being.
For the injector, the drive timing of which is closely related to the operation condition of the engine, it is not easy to change the drive timing, arbitrarily. Also, with the high-pressure fuel pump (for example, a fuel pump of a variable capacity type), having the structure of controlling the discharge flow amount by changing the drive timing thereof, it is impossible to keep a common rail pressure at a desired pressure, since the discharge flow amount is changed when the drive timing thereof is altered.